By Barney Richardson

With the now ever-increasing use of flammable refrigerants, practitioners must be very aware of the safety requirements when working on refrigeration units using these gases.

This point was mentioned in a previous article, and I wonder who took the time to read this, absorb and understand the dangers.

We’ve been using non-flammable refrigerants since the 1930s and 1940s. They are now being phased out at a very fast pace. With the movement to hydrocarbon refrigerants, what are the new procedures and practices that must be followed by practitioners in handling flammable refrigerants?

Where are these refrigerants being used?

First, we see R290 used in domestic refrigerators and beverage coolers. Then R600a is also used in ice makers and refrigeration units. I was in the UK in November and saw an ice maker on a counter producing a dozen ice cubes every 7 minutes running on R600a. We are aware that room air conditioners are soon to be introduced that will be on R600a.

The same procedures and methods we apply for the common refrigerants we use now, will also apply to flammable A2L, A2 and A3 refrigerants. Do you remember in a previous column, I provided the chart for the classification of refrigerants? Refrigerants that are operating under pressure is why the Department of Employment and Labour introduced the Pressure Equipment Regulations into the OHS Act in July 2009. This is also why, for safety reasons and compliance, you’ve got to be a registered practitioner and be careful when you’re handling flammable refrigerants.

During transportation cylinders must be kept upright, they too have to be secured properly in storage and during transportation.

The work zone when carrying out service and repair, a two-meter flame hazard zone in all directions of an outdoor condensing unit and, if indoors from the refrigeration appliance, is required. If the area is a confined space within a building like a plant room, the area must be well ventilated. These are the same procedures that apply to the common refrigerants and will still apply to the three classification levels for flammable refrigerants.

Then, there is the Refrigerant Concentration Limit (RCL), (ASHRAE standard 34 – 2019) this limit in air is determined in accordance with this standard and intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces. This essentially means the amount of refrigerant allowable in a space if there is leakage.

With an A2L refrigerant like R32 which has a lower flammability, the concentration can be calculated. The table below: from the United Nations Environment Programme, Economy Division, OzonAction and the Pacific Islands Countries Guide; shows recommended refrigerant charge for R32 in unit types in various positions and floor areas.

Table 1: Maximum allowable charge of R-32 in kilograms for air-conditioning units for various positions installed(KG)


Floor mounted

Window mounted

Wall mounted

Ceiling mounted

Max Kg charge

Max Kg charge

Max Kg charge

Max Kg charge































Engineers, installers and servicing technicians must ensure that the actual charge size of refrigerant in an air conditioning or refrigeration system being installed or serviced does not exceed the maximum charge size, and must further be aware of these limitations.

The charge limits have increased from 150g to 500g for the most flammable A3 refrigerants. For mildly flammable alternatives (A2 and A2L), the limit has increased from 150g to 1.2kg. This was already changed in 2019 by the International Electrotechnical Commission (IEC) in the revised safety standard IEC 60335-2-89. The new higher limits only apply to some applications and only in rooms of a certain size as indicated in the table above. 

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